$ E = \left[\begin{array}{rrr}2 & 2 & 2 \\ 0 & 2 & 2 \\ 2 & 1 & 2\end{array}\right]$ What is $ E^{-1}$ ?
Explanation: $ = \left[\begin{array}{rrr}\frac{1}{2} & -\frac{1}{2} & 0 \\ 1 & 0 & -1 \\ -1 & \frac{1}{2} & 1\end{array}\right]$